Optimized device for digital data communication in a microcircuit card

Abstract

A microcircuit card includes input/output elements ( 14 ) for digital data, elements for processing ( 12 ) the data and control elements ( 26 ). The processing elements ( 12 ) include members for transferring digital data (DMA) between the input/output elements ( 14 ) and a storage zone ( 18 ), and elements for communicating with the control elements ( 26 ), control data obtained at the digital data. The control elements ( 26 ) control the transfer of the digital data by the transfer elements (DMA) taking into account the control data.

1 . Microcircuit card including: 
 input-output means ( 14 ) for digital data (DATA);    processing means ( 12 ) for processing this data; and    stream control means ( 26 ),    the microcircuit card being characterized in that the processing means ( 12 ) include:    transfer means (DMA) for transferring said digital data (DATA) between the input-output means ( 14 ) and a storage area ( 18 ); and    communication means ( 20 ) for communicating with the stream control means ( 26 ) security data (DATA_CTRL) obtained from said digital data (DATA),    the stream control means ( 26 ) being adapted to control the transfer of the digital data (DATA) by the transfer means (DMA) taking into account said security data (DATA_CTRL).    
   
   
       2 . Microcircuit card according to  claim 1 , characterized in that said security data (DATA_CTRL) consists at least in part of a portion of said digital data (DATA).  
   
   
       3 . Microcircuit card according to  claim 2 , characterized in that said security data (DATA_CTRL) includes authentication data (AUTH) for authenticating a portion (P 1 ) of the digital data received by the card, the stream control means ( 26 ) being adapted to verify the validity of said digital data (DATA) on the basis of this authentication data (AUTH) and to control said transfer as a function of the result of this verification.  
   
   
       4 . Microcircuit card according to  claim 1 , characterized in that said processing means ( 12 ) are adapted to insert into said security data (DATA_CTRL) a result of processing said digital data (DATA).  
   
   
       5 . Microcircuit card according to  claim 4 , characterized in that said processing result is the result of a step of authenticating said digital data.  
   
   
       6 . Microcircuit card according to  claim 1 , characterized in that the stream control means are adapted to modify at least one operating parameter of said transfer means (DMA).  
   
   
       7 . Microcircuit card according to  claim 6 , characterized in that said parameter is selected from an address of said storage area ( 18 ) and a parameter for selecting a protocol for communication between the input-output means ( 14 ) and the storage area ( 18 ).  
   
   
       8 . Microcircuit card according to  claim 1 , characterized in that said processing means ( 12 ) include a data compression unit ( 13 ), a data decompression unit, a data encryption unit or a data decryption unit.  
   
   
       9 . Microcircuit card according to  claim 1 , characterized in that said stream control means ( 26 ) are adapted to stop the transfer of the digital data (DATA) by said transfer means (DMA) if they detect the presence of invalid authentication data in said digital data (DATA) on the basis of said security data (DATA_CTRL).  
   
   
       10 . Microcircuit card according to  claim 1 , characterized in that the stream control means ( 26 ) are further adapted to obtain preliminary data directly from the input-output means ( 14 ), the stream control means ( 26 ) also taking account of the preliminary data in authorizing or refusing the transfer of the digital data (DATA) by the transfer means (DMA).  
   
   
       11 . Microcircuit card according to  claim 10 , characterized in that said preliminary data includes authentication data (PASSWD).  
   
   
       12 . Microcircuit card according to  claim 10 , characterized in that said data includes a storage address for said digital data.  
   
   
       13 . Microcircuit card according to  claim 1 , characterized in that it further includes regulation means (PLL) adapted to modify a clock frequency applied to the processing means ( 12 ) as a function of said security data (DATA_CTRL).  
   
   
       14 . Microcircuit card according to  claim 1 , characterized in that said transfer means (DMA) include a DMA component.  
   
   
       15 . Microcircuit card according to  claim 11 , characterized in that said data includes a storage address for said digital data.